This invention relates generally to infrared medical thermometers and, more particularly, to infrared medical thermometers of a kind having an elongated probe adapted for insertion into a patient's ear canal.
Medical or clinical thermometers of this particular kind show great promise as an effective means for accurately measuring patient temperatures very rapidly, typically within several seconds. The inner ear is known to have a temperature very near to that of the body's core temperature, and infrared radiation transmitted from the eardrum and immediately surrounding tissue can therefore be a good indicator of the patient's body temperature. In addition, the thermometers provide minimal inconvenience and discomfort to the patients.
Infrared medical thermometers of this kind include an infrared radiation sensor having a hot junction exposed to the patient's ear canal and a cold junction maintained at a fixed, or at least known, temperature. The sensor generates a signal proportional to the temperature difference between the hot and cold junctions, whereby the patient's body temperature can be accurately ascertained.
One difficult problem that has been encountered in infrared thermometers of this kind is the maintenance of the infrared sensor's cold junction at a fixed or known temperature. Particularly troublesome in some situations is the prevention of heat from traveling from the ear canal to the cold junction.
It should, therefore, be appreciated that there is a need for an effective probe configuration for an infrared medical thermometer that effectively insulates the cold junction of its infrared sensor and prevents heat from the ear canal or other source from reaching that cold junction. The present invention fulfills that need.